With the current rapid development of telecommunication technologies, new projects of mobile value-added services for both mobile and fixed phones have emerged continuously to meet increasing personalized demands of mobile users. For instance, Multimedia Message Services (MMS), Interactive Voice Response (IVR), voice short message, etc. have emerged as value-added services for mobile phones. Moreover, the color ring back tone service established since 2003 has brought a further increased Average Revenue Per Unit (APRU) to telecommunication operators.
The color ring back tone service, also referred to as a personalized ring back tone service, is such a service that can be subscribed to by a user for providing a caller user with a segment of musical song or another audio record instead of an ordinary ring back tone. With subscription to the color ring back tone service, a customer can set a personalized ring back tone freely, and while this user is being called, a musical song or another audio record subscribed to in such a personalized way, instead of an ordinary ring back tone, can be played for the caller user. Specifically, a personalized ring back tone can be any segment of music, song, audio record, video, etc. In the case of video, a terminal of the caller user is required to be capable of playing video media for the purpose of proper experience, and the service is also referred to as a multimedia color ring back tone or color video service. Essentially, an ordinary ring back tone and a color ring back tone including a multimedia color ring back tone each are a controlled media resource in a packet domain, and thus in the present specification, are collectively called a “ring back tone”, and their corresponding media resources are collectively called a “ring tone resource”.
On the other hand, in value-added services for fixed phones, call forwarding is a common service which was early put into use, and specifically refers to that for a subscriber to this service, an incoming call, which has not been answered by the subscriber (original called user), can be forwarded to another user (forward-to user) or a voice mail. The call forwarding service includes but is not limited to Call Forwarding Unconditional, Call Forwarding on Busy, Call Forwarding on No Reply, etc. The Call Forwarding on No Reply refers to that any incoming call for a subscriber to the service, which has not been answered within a specified time limit, is forwarded automatically to a pre-specified number. The Call Forwarding on Busy refers to that an incoming call for a subscriber to the service on busy can be forwarded automatically to another specified number. Such a service allows an incoming call for a subscriber to be forwarded to another number. The Call Forwarding Unconditional refers to that any incoming call for a subscriber to the service can be forwarded automatically to a pre-specified number despite the status of the called subscriber. The call forwarding service can satisfy the requirement of a user for flexible processing of an incoming call, and thus increasingly win the favor of various users.
In the present specification, a destination user called by a caller user will be referred to as a “called user” regardless of whether call forwarding occurs during the call. A forwarding destination user for the called user with which the call forwarding occurs and a further forwarding destination user for the forwarding destination user with which further call forwarding occurs will be collectively referred to as a “forward-to user”.
However, some problems may arise from the combination of the call forwarding service with a new value-added service, for instance, the combination of the call forwarding service with a color ring back tone service. By way of example, a caller user A calls a called user B who has subscribed to a color ring back tone service and for whom a call forwarding service has been activated, and thus the call from the caller user A is forwarded to a forward-to user C who has also subscribed to a color ring back tone service. The forward-to user C accepts the call, and consequently his terminal rings. In such a case, both the called user B and the forward-to user C have subscribed to a color ring back tone service, resulting in a problem that a color ring back tone subscribed to by which of the users shall be played for the caller user A.
At present, a simplest solution to this problem is that a caller user is made to always hear a color ring back tone subscribed to by a final forward-to user despite how a call has been forwarded. In other words, in the above example, the caller user A hears a color ring back tone subscribed to by the forward-to user C.
In practical operation, however, an operator may require that a caller user hear a color ring back tone subscribed to by an original called user despite how a call has been forwarded. In other words, in the above example, the call user A shall hear a color ring back tone subscribed to by the called user B. Even if the called user B has not subscribed to the color ring back tone service, but the forward-to user C has subscribed to the color ring back tone service, the caller user A will hear an ordinary ring back tone instead of a color ring back tone subscribed to by the forward-to user C.
The operator has such a requirement because the color ring back tone service is a subscribed service which serves a called user, but it is a caller user that experiences the service. The caller user calls a familiar called user, and during connecting of the call, he is generally not aware that the call has been forwarded. When hearing a color ring back tone subscribed to by a final forward-to user, the caller user may be puzzled or even think that he has dialed a wrong number and hence hang up. Additionally, in the case that the activated call forwarding is the Call Forwarding on No Reply, the terminal of the original called user actually have been connected and thus rung, and the caller user may have heard a color ring back tone (or an ordinary ring back tone) triggered by the original called user. Only when there is no reply after the terminal of the original called user has rung for a period of time, the call will be forwarded. If the caller user is made to hear a color ring back tone subscribed to by the final forward-to user, such a switching of color ring back tone may bring an unpleasant service experience to him/her.
As can be seen, a good service experience can be provided for the caller user in the event that “regardless of how a call has been forwarded, when the call is put through, that is, a terminal of a forward-to user rings, the caller user can always hear a color ring back tone or an ordinary ring back tone triggered by the original called user until the call is answered for a talk or fails”, as desired by the operator.
However, in a current packet core network using the SIP as call control signaling, there is no standard call flow available for such a service. Thus there is a need for development of a solution to this service in a packet core network using the SIP as call control signaling.